Tank System

ABSTRACT

A vessel including an inlet to receive fluids; at least five side walls configured in a polygonal shape, a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls, and an outlet coupled to the lower angled section is disclosed. A system of vessels including a first vessel and a second vessel, each including an inlet to receive fluids, at least five side walls configured in a polygonal shape, a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls, and an outlet coupled to the lower angled section, wherein the first vessel and the second vessel have at least one common side wall is also disclosed.

FIELD OF THE INVENTION

The present disclosure relates generally to an apparatus for providing storage of fluids, solids or liquids. In particular, the present disclosure relates to a polygonal shaped vessel. More particularly, the present disclosure relates to a plurality of polygonal shaped vessels for saving space on an offshore oil rig.

BACKGROUND OF INVENTION

Oil rigs, particularly off-shore rigs, need to utilize all available space efficiently due to the number of processes that are performed and the limited amount of space provided. Most off-shore oil rigs include numerous levels or platforms and utilize gravity to move fluids between the levels, minimizing the number of pumps on the oil rig.

Various fluids (“well fluids”) may be used on the oil rig and may include both solids and liquids. Common uses for well fluids include: lubrication and cooling of drill bit cutting surfaces while drilling generally or drilling-in (i.e., drilling in a targeted petroleum bearing formation), transportation of “cuttings” (pieces of formation dislodged by the cutting action of the teeth on a drill bit) to the surface, controlling formation fluid pressure to prevent blowouts, maintaining well stability, suspending solids in the well, minimizing fluid loss into and stabilizing the formation through which the well is being drilled, fracturing the formation in the vicinity of the well, displacing the fluid within the well with another fluid, cleaning the well, testing the well, implacing a packer fluid, abandoning the well or preparing the well for abandonment, and otherwise treating the well or the formation.

Since space is a priority on an oil rig, the storage of fluids must be done efficiently. These fluids include various components that may be recycled and re-used or may be treated prior to disposal. Between the various operations, these fluids may be temporarily stored in a tank system. For example, when a wellbore fluid brings cuttings to the surface, the mixture is typically subjected to various mechanical treatments (shakers, centrifuges, etc) to separate the cuttings from the recyclable wellbore fluid. However, the cuttings may need to be treated or the recyclable wellbore fluid may need to be stored until it is used again.

Typically, storage vessels are provided on a lower level of the platform and gravity is used to provide the fluids to them. Circular cross-section vessels are easy to clean but are an inefficient use of space. Rectangular (or square) cross-section vessels are an efficient use of space but are difficult to clean. Accordingly, there exists a need for a tank system which efficiently uses space, maintains the integrity of the vessels and is easy to clean.

SUMMARY OF INVENTION

In one aspect, embodiments disclosed herein relate to a vessel that includes an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section.

In another aspect, embodiments disclosed herein relate to a system of vessels comprising at least two vessels of polygonal shape and having at least one common side wall between adjacent vessels.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A shows a perspective view of a vessel in accordance with embodiments disclosed herein.

FIG. 1B shows a top view of the vessel of FIG. 1A in accordance with embodiments disclosed herein

FIG. 2A shows a perspective view of a vessel in accordance with embodiments disclosed herein.

FIG. 2B shows a top view of the vessel of FIG. 2A in accordance with embodiments disclosed herein

FIG. 3A shows a top view of a vessel assembly in accordance with embodiments disclosed herein.

FIG. 3B shows a top view of a vessel assembly in accordance with embodiments disclosed herein.

FIG. 4 is a partial view of a conventional off-shore drilling rig in accordance with embodiments disclosed herein.

FIG. 5A shows a top perspective view of a vessel assembly in accordance with embodiments disclosed herein.

FIG. 5B shows a bottom perspective view of the vessel assembly of FIG. 5A in accordance with embodiments disclosed herein.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to a vessel. More specifically, embodiments disclosed herein relate to a system of vessels for storing fluids on an oil rig.

Referring to FIGS. 1A and 1B, a vessel according to one embodiment of the present disclosure is shown. As shown in FIG. 1A, a vessel 20 has an upper end 20 a, a body section 20 b, and a lower section 20 c. At the lowermost end of the lower section 20 c, the vessel is provided with an outlet 25. In a preferred embodiment, the upper end 20 a is open to the atmosphere. In other embodiments, the upper end 20 a may be enclosed, and the vessel 20 may be a pressurized vessel. The body section 20 b may include at least five side walls 30 a provided in a polygonal shape. The lower section 20 c may include at least five bottom walls 30 b arranged to provide the outlet 25. In a preferred embodiment, the body section 20 b includes six side walls 30 a providing a hexagonal shape and six bottom walls 30 b arranged to provide the outlet 25. Baffles (not shown) may be provided in the vessel 20 to alleviate caking on the walls of the vessel 20 as well as to promote the discharge of material in the vessels. To prevent agglomeration of fluids, the vessel 20 may also include an agitator (not shown), such as a paddle shape type.

Due to the angle of the lower section 20 c being less than a certain value, the material flow out of the vessel is of the type known as mass flow and results in all of the material exiting uniformly out of the vessel. In the case of mass flow, fluid in the vessel descends or moves in a uniform manner towards the outlet, as compared to funnel flow (a central core of material moves, with stagnant materials near the hopper walls). It is known that the critical hopper angle (to achieve mass flow) may vary depending upon the material being conveyed and/or the vessel material. In various embodiments, the angle (from the vertical axis) for mass flow to occur may be less than 40°. One of ordinary skill in the art would recognize that in various embodiments the lower section 20 c may be conical or otherwise generally pyramidal in shape or otherwise reducing in nature, e.g., a wedge transition or chisel, to promote mass flow. In a particular embodiment, the lower angled section has a minimum discharge dimension of at least 12 inches (300 mm). The lower section 20 c of the vessel 20 may be round and provide a round discharge 25.

Referring to FIGS. 2A and 2B, in an alternate embodiment, the body section 20 b may include eight side walls 30 a providing an octagonal shape and eight bottom walls 30 a arranged to provide the outlet 25. One skilled in the art will appreciate that any number of side walls 30 a may be provided in a polygonal shape with a corresponding number of bottom walls 30 b, or round bottom, arranged to provide an outlet 25. In alternate embodiments, the vessel 20 may have a polygonal shaped exterior and a round interior.

Referring to FIGS. 3A and 3B, a plurality of vessels 20 may be provided as a tank system 40. The plurality of vessels 20 are preferably manufactured to provide adjacent vessels 20 having at least one common side wall 30 a. FIG. 3A illustrates a three tank system and FIG. 3B illustrates a four tank system. One skilled in the art will appreciate that any number of vessels 20 may be provided in a polygonal shape wherein adjacent vessels 20 have at least one common side wall 30 a. The tank system 40 may have the vessels 20 manufactured together to provide the common side wall 30 a while reducing the number of side walls 30 a.

Referring to FIG. 4, an offshore rig 10 having multiple levels 100, one of which may be suited for the storage of drilling fluids as performed according to one embodiment of the present disclosure is shown. On a platform 100 b, drill cuttings may undergo traditional screening processes 110. From the screening process, solids, liquids, or combinations thereof may be loaded into one or more vessels 20. The vessels 20 may be configured in the tank system 40, of which there may be two or more vessels 20. From vessels 20, solids may exit the vessels 20 and be sent for further processing while the liquids may exit the vessel and be disposed off the platform or otherwise saved for reuse. In certain embodiments, there may be six vessels 20 a through 20 f. One of ordinary skill in the art would recognize that the number of vessels may be determined by the size and operation of the rig 10 for various embodiments.

The discharge 25 of the vessels 20 may be connected to a discharge valve 125 b, which is further connected to a pipe 125. A filling pipe 122 extends into the vessel 20 f via an inlet valve 122 a. Also extending into vessel 20 f may be a secondary filling pipe 124. The filling pipe 122 or secondary filling pipe 124 may extend into any of the vessels 20 and may in fact extend into all vessels 20. In other embodiments, the vessels 20 may be manufactured to provide a shared discharge and a shared length of pipe.

In some embodiments, also extending into the vessel 20 may be an automatic tank cleaning system (ATC) 128, such as those manufactured by MI-SWACO, LLC of Houston, Tex. Not every vessel 20 includes the ATC 128, the ATC 128 may be optional for the vessels 20 and may not be provided for all vessels 20 on the rig 10.

The polygonal shape of the vessels 20 provides an efficient, space-saving design. By manufacturing the tank system 40 to have vessels 20 with a common side wall, less material may be used while providing a rigid vessel.

In a filling operation, prior to loading fluid into vessel 20, discharge valve 125 b is closed. The inlet valve 122 a is opened, and the fluids are fed into the vessel 20 f. In a preferred embodiment, the vessels 20 may be fluidly connected to provide a mechanism of filling all vessels with only a single filling pipe 122. In some embodiments, the vessels 20 are fluidly connected via one or more apertures in the common wall between adjacent vessels, allowing fluid to flow from one vessel to another through the apertures. Alternatively, the vessels are fluidly connected via the common wall between adjacent vessels, allowing fluid to flow from one vessel to another over the common wall. In order to empty the vessel 20, valve 125 b is opened, and gravity forces the fluid out of the vessel 20 and into pipe 125. In an alternate embodiment, if the vessel is pressurized, compressed air or another gas may be used to discharge the fluid from the vessel 20. In a particular embodiment, the compressed gas applied to the pressurized vessel may be within a pressure ranging from about 4 to 8 bar.

Referring to FIGS. 5A and 5B, a plurality of vessels 20 may be provided as a tank system 50 for use in a shaker pit process. The plurality of vessels 20 are preferably manufactured to provide adjacent vessels 20 having at least one common side wall 30 a. FIGS. 5A and 5B illustrate an eight tank system having discrete subsystems.

The tank system 50 may include a dedicated tank 20 a capable of acting as a multiphase clarifier (MPC). The MPC can be used to drain runoff from the various levels of the offshore rig including the shaker house, rig floor, main deck and, helicopter deck. The MPC provides first-stage separation of waste stream runoff offshore due to waste stream runoff. The MPC may provide for separation of any oil and water-based drilling fluid systems. Further, the MPC has the ability to break the drain runoff from multiple areas such as the rig floor and the shaker deck, into three waste streams, for example, water, mud/base oils, and solids. The waste stream separation may occur without chemical or mechanical assistance. The MPC also may enable automated separation, collection, routing and processing of varying degrees of emulsified mixtures. The MPC is capable of separating solids in heavy fluids/muds, separating water from oil, sending each waste stream to a desired location, and minimizing volumes for post-treatment. Post-treatment processes may include further processing including, but not limited to, shakers, centrifuges, hydrocyclones or the like. Tank 20 a also includes a discharge valve 125 a. The MPC tank 20 a may also be sized for a larger volume as compared to other tanks in the tank system.

The tank system 50 may also include five dedicated tanks 20 b for use as shaker pits. These tanks 20 b preferably provide storage for the return mud flow. The discharge 25 b of the vessels 20 b may be connected to a discharge valve 125 b, which is further connected to a pipe 135 b. The pipe 135 b may be connected to an active mud system. An unrestricted overflow pipe 70 may be included in one or more of the tanks 20 b. The pipe 70 may be connected to pipe 135 b.

The tank system 50 may also include two dedicated completion tanks 20 c for completion operations. Completion tanks 20 c may be lined/coated for ease of cleaning and resistance to abrasive properties of completion fluids. Tank 20 a and tanks 20 b may be also lined/coated for ease of cleaning and resistance to abrasive properties of the fluids they may process. The liner of the tanks may be any liner or coating known to one skilled in the art such as, but not limited to, polyurethanes, epoxies, polytetrafluoroethylenes (PTFE) and the like. The discharge 25 c of the completion tanks 20 c may be connected to a discharge valve 125 b, which is further connected to a pipe 145 b. The pipe 145 b may be connected to an active fluid or completion system.

One skilled in the art will appreciate that a wide variety of discrete subsystems may be combined to form a tank system providing a variety of discrete processes. The discrete subsystems may have varying numbers of associated tanks, dependent upon the requirements of the discrete processes. Discrete processes may include cleaning, storage, processing, completion, workover, production and the like known to one skilled in the art.

One of skill in the art will appreciate that a wide variety of materials may be used in the construction of the above described vessel. In one such illustrative embodiment, a vessel is constructed of welded metal, such as steel, steel alloys, aluminum, aluminum alloys, and the like, which may subsequently be coated with paint, epoxy, thermoplastic and other such protective materials. Alternatively, the vessel may be constructed from composite materials including resin based composites, such as: fiberglass/resin; carbon fiber/resin; metal fiber/resin; combinations of these and the like, thermoplastic composites such as fiberglass/plastic; carbon fiber/plastic; metal fiber/plastic; combinations of these and the like; as well as combinations of various composite materials that are suitable for such applications. Finally it should be noted that one of skill in the art will appreciate that the illustrative vessels may be cast, stamped, forged, or machined from ferrous and non-ferrous metals, plastics, composite materials and the like.

While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the present disclosure. Accordingly, the scope of the present disclosure should be limited only by the attached claims. 

What is claimed is:
 1. A vessel comprising: an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section.
 2. The vessel of claim 1 further comprising an agitator.
 3. The vessel of claim 1 further comprising an automatic tank cleaner.
 4. The vessel of claim 1 having six side walls configured as a hexagon.
 5. The vessel of claim 1 having eight side walls configured as an octagon.
 6. The vessel of claim 1 wherein the lower angled section comprises at least five bottom walls.
 7. The vessel of claim 4 wherein the lower angled section comprises six bottom walls.
 8. The vessel of claim 1 further comprising internal baffles.
 9. The vessel of claim 1 comprises a pressurized vessel.
 10. A system of vessels comprising: a first vessel; and a second vessel; wherein the first vessel and the second vessel each comprise: an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section wherein the first vessel and the second vessel have at least one common side wall.
 11. The system of vessels of claim 10 wherein the first vessel and the second vessel are fluidly connected via one or more apertures in the common wall between the first vessel and the second vessel.
 12. The system of vessels of claim 10 wherein the first vessel and the second vessel are fluidly connected via the common wall between the first vessel and the second vessel.
 13. The system of vessels of claim 10 wherein the first vessel and the second vessel have a common discharge coupled to the outlet of each vessel.
 14. The system of vessels of claim 10 further comprising a third vessel comprising an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section wherein the second vessel and the third vessel have at least one common side wall, and wherein the first vessel and the third vessel have at least one common side wall.
 15. The system of vessel of claim 14 wherein first vessel, second and third vessel are fluidly connected.
 16. The system of vessels of claim 14 further comprising a fourth vessel comprising an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section wherein the fourth vessel and the first vessel have at least one common side wall, and wherein the fourth vessel and the third vessel have at least one common side wall.
 17. The system of vessel of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel are fluidly connected.
 18. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel further comprise an agitator.
 19. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel further comprise an automatic tank cleaner.
 20. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel further comprise six side walls configured as a hexagon.
 21. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel further comprise eight side walls configured as an octagon.
 22. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel further comprise internal baffles.
 23. The system of vessels of claim 16 wherein the first vessel, second vessel, third vessel, and fourth vessel are pressurized vessels. 